gistfile1.rb

        | wrap(all_with_tag('ReleaseDate') do |x|
                 if x.values.first.nil?
                   nil
                 else
                   x[x.keys.first] = Time.parse(x.values.first)
                   x
                 end
               end |
          (allowed_dates.nil? ? nil : select{ |x| allowed_dates.cover? x.values.first}) |